Movable Sleeve Master Key Lock Cylinder
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Solution Overview
Problem
Wafer tumbler locks lack a master key capability, requiring multiple part numbers for fabrication and are not backwards compatible with existing locks, making them less secure and prone to picking.
Innovation Solution
A master keying system utilizing a movable sleeve that shifts the locking surface within the lock casing relative to the wafer tumblers, allowing both original and master key access, while maintaining security and compatibility with existing tumblers and keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wafer tumbler lock is designed to work with a single original key, then the lock structure is simple and easy to manufacture, but the lock lacks master key capability and requires multiple part numbers for different key configurations
Solution Approach 1:
The patent applies the dynamics principle by introducing a movable sleeve that can shift between two positions: a first position where the locking surface engages the wafer tumblers for normal key operation, and a second position where the locking surface is offset to allow master key operation. This dynamic repositioning of the locking surface enables the lock to adapt between single-key and master-key modes without requiring fundamentally different lock structures.
Solution Approach 2:
The patent employs dimensionality change by adding an axial dimension to the locking surface position. The locking surface can be positioned at different axial locations relative to the wafer tumblers, creating distinct operational modes. This axial displacement allows the same locking surface to serve multiple functions by changing its position along one dimension, rather than requiring multiple separate locking surfaces.
2Adaptability or versatility
If a master keying system is added to existing wafer tumbler locks, then multiple keys can access the lock, but the lock is not backwards compatible with existing locks and requires coordination of many different part numbers
Solution Approach 1:
The patent implements universality by designing a single lock body that can universally accept both original keys and master keys through the movable sleeve mechanism. The same lock body, with its movable locking surface, serves multiple functions: it operates as a standard single-key lock when the sleeve is in the first position and as a master-key-enabled lock when the sleeve is in the second position. This eliminates the need for different part numbers for different key configurations.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the lock with a movable sleeve that can be positioned to enable master key capability from the outset. The locking surface is designed with offset positions that are prepared in advance, allowing the lock to accommodate master keys without requiring field modifications or coordination of multiple part numbers. The movable sleeve mechanism is pre-engineered to provide both operational modes.
3Adaptability or versatility
If the locking surface is fixed relative to the wafer tumblers, then the lock is secure against picking, but the lock cannot accommodate master keys or sleeve manipulation
Solution Approach 1:
The patent uses dynamics by making the locking surface movable rather than fixed. The sleeve can shift between positions, dynamically changing the relationship between the locking surface and the wafer tumblers. When in the first position, the locking surface aligns with the tumblers for secure operation. When in the second position, it offsets to allow master key operation, providing flexibility while maintaining security through controlled movement.
Data Source
AI summary
A master key lock includes a lock cylinder having a keyway for receiving a key, a sleeve about the cylinder, a plurality of wafer tumblers, a master key and a spring operable to axially move the sleeve relative to the cylinder when the master key is inserted into the keyway. A system that uses the master key lock includes a lock case wherein the sleeve is disposed between the cylinder and the lock case, the sleeve being axially movable within the case. The sleeve comprises a plurality of transversely disposed slots for engaging the plurality of wafer tumblers such that the lock is unlocked by insertion of a key or a master key. A method of using the master key lock is also disclosed.